Residual wastes are often generated during industrial processes. In the context of oil refineries, the residual wastes may include byproducts of the refinement process. These wastes may be solids including, but not limited to, dirt, sand, grit, paraffin, wax, and/or emulsified oil. Solids accumulating inside of a ground tank settle on a tank bottom which, over time, may undermine the productivity of the tank. For example, a tank 120 feet in diameter with a height of 40 feet, may accumulate tens of feet of build up at the tank bottom, reducing its capacity and rendering it inefficient or unsuitable for use.
In the context of gasoline refineries, a catalyst is often used to start a reaction to initiate the processing of gasoline. Such catalysts may include an aluminum catalyst known as CC catalyst, or other precious-metal catalysts such as an FCC catalyst or palladium catalyst. When the catalyst is added, it can be in the form of a solid (e.g., a dry powder), which can later be extracted using one or more filters following the completion of the gasoline refinery process.
In some instances, a breach may occur in one of the pieces of equipment that allows catalyst to flow from a cat cracker during the processing. This flow is sometimes referred to as slop oil. When slop oil escapes and refineries try to process it, the slop oil may combine with the catalyst to form a thick layer of solids that settle onto the tank bottom. In certain scenarios, 60% to 70% of the solids at the bottom of a tank, such as, for example, a refinery tank, may comprise the slop layer. Other solids that rest on the tank bottom may include dirt, sand, grit, paraffin, wax, and emulsified oil. These solids may accumulate with time on the tank bottom and require cleaning.
Traditionally, in order to clean the refinery tanks, refineries pump liquids into the refinery tank, mix the liquids and solids, and extract a blend for centrifuging outside the refinery tank. The centrifuged mixture of solids and liquids are then transported from the location of centrifuging to an industrial burner (e.g., cement kiln) for disposal of the waste materials. These methods can be costly due to the costs associated with roll-off container rental, repair, and cleaning; shipping, storage, etc. Additionally, a considerable amount of resources are expended tracking the hazardous materials as they are extracted from the refinery tanks and loaded and unloaded at the centrifuge and the kiln.
Refinery tanks may remain in service or taken out of service as the waste is removed from the refinery tank. Where a slop layer is present, however, cleaning may be made difficult. Before the removal of any solids, the slop layer should be removed. This can take months, requiring the tank to be taken out of service, which can add expense. Accordingly, there is a need for an efficient process to remove, process, transport and dispose of the solids from a refinery tank.